A unique example of international co-operation is given in the program of research on radiation from flames in industrial furnaces that is being conducted at the Royal Netherlands Blast Furnace and Steel Works. Financial support and direction came first from the Netherlands, France, and Great Britain. These countries have now been joined by Belgium, Sweden, the United States, and the High Authority of the European Community of Coal and Steel. This paper outlines the organization of the work, the experimental facilities, the methods of research, and presents the outstanding results on the effect of the variables studied on flame radiation. These variables have been the type of fuel oils or coke-oven gas, the rate of heat input, the type and rate of supply of atomizing agent, the type of burner, the excess of air, the type and amount of carbureting agent for gas, and the temperature of the combustion air. Of these several variables, the C/H ratio of the oil and gas fuels and the mixing conditions most markedly affect the emissivity and the radiation of the flames. The results point to the need for further knowledge of the relation of the radiating characteristics of flames to the rate of heat transfer to “work” in furnaces. The research has now been extended to include the use of pulverized coal.